This application is based upon Japanese Patent Application No. 2001-311677, filed on Oct. 9, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a vehicle air conditioner, especially one which conditions the air in a vehicle in accordance with the amount of sunlight incident into a passenger compartment of the vehicle.
2. Related Art
In a conventional air conditioner, a target blowing temperature TAO of the air blown into the passenger compartment is calculated for conditioning the air in the vehicle in association with detected signals indicative of sensors, positioned in various places of the vehicle, such as an inside air temperature sensor, an outside air temperature sensor, or a sunlight amount sensor. Then, the air conditioner calculates a control value based on the TAO for controlling an actuator such as a servo motor which rotates a switching door and a blower fan which determines the amount of the blown air.
Namely, the air conditioner automatically controls the temperature of the air blown into the passenger room, the amount of the blown air, and a blow-out mode based on the value obtained from the TAO which is determined by the detected signals from the sensors that are inputted to a controller as well as a preset temperature inputted by the passenger.
When one of the detected signals changes, the air conditioner may change the temperature of the air blown into the passenger room, the amount of the blown air, and the blow-out mode. Typically, the amount of sunlight changes frequently according to the change in the traveling direction of the vehicle. For calculating the TAO by precisely detecting the changeable amount of the sunlight, a method for detecting the amount of the sunlight with time delay by applying the time constant to the detected value of the sunlight amount has been employed. Therefore, the TAO is calculated after the predetermined time elapses.
FIG. 1A shows a case of a traveling pattern of the vehicle where the vehicle changes a traveling direction from a first direction in which the vehicle receives the sunlight from its rear side to a second direction in which the vehicle receives the sunlight from its left side after traveling in the first direction about 10 seconds, and keeps the second direction for a while (about 20 seconds in this case), then, the vehicle changes again its traveling direction to the direction in which the vehicle receives the sunlight from its rear side. When the air is conditioned using the above-described method while the vehicle is receiving the sunlight from the left side in this case, the air conditioning will not be performed because of the time delay in changing the TAO even if a passenger positioned the left side in the vehicle feels uncomfortable by increase of his/her skin temperature caused by the incident sunlight.
On the other hand, when the air is conditioned using a conventional method without the time delay in calculating the TAO, that is, the conditioning of the air, especially the amount of the blown air Va is changed immediately after the amount of the sunlight changes as shown in FIG. 1B, the increase of the skin temperature can be suppressed while receiving the incident sunlight and a temperature sensation can be kept at a satisfactory level. However, the temperature sensation is not good enough for the passenger because the amount of the blown air Va is changeable relatively in a short time in accordance with change in the target blowing temperature TAO calculated by using detected sunlight amount that is very changeable.
An object of the invention is to provide an improved vehicle air conditioner that controls air conditioning comfortably.
According to a first aspect of the present invention, the air conditioner conditions the air based on the amount of sunlight that has a value before changing when the change in the amount of sunlight is equal to or less than a predetermined amount.
When the change in the amount of sunlight is small such that the temperature sensation level does not change to an uncomfortable level, the air conditioner keeps a condition before the amount of sunlight changed by using a fixed value of the amount of sunlight. Therefore, the temperature sensation is not influenced because the amount of blown air can be kept at a condition before the amount of sunlight changed.
According to another aspect of the present invention, when the situation where the change in the amount of sunlight is lower than the predetermined amount is kept for a predetermined time, the air conditioner conditions the air using the updated amount of sunlight based on information detected by a sunlight amount detector. Namely, in a situation where the amount of sunlight changes frequently in a short time, the amount of the blown air is kept at a condition before the amount of sunlight changed.
According to another aspect of the present invention, when the change in the amount of sunlight exceeds the predetermined amount in such a level that the skin temperature of the passenger to whom the sunlight is incident increases so that the temperature sensation becomes an uncomfortable level, the air conditioner controls the blow-out direction of the conditioned air so that the conditioned air is blown toward a passenger to whom the sunlight is incident.
According to another aspect of the present invention, by using a navigation system for performing the travel guide of a vehicle by detecting a current position and a traveling direction of the vehicle and using them and information previously memorized, the amount of sunlight incident into the vehicle can be obtained in accordance with the present data and the present time. Also, the change in the amount of sunlight can be obtained.
The navigation system obtains the location of the sun in accordance to the present data and the present time, obtains the sunlight direction based on the location of the sun and the road information, and obtains the amount of sunlight incident into the vehicle in association with the direct incident sunlight amount that reaches the ground based on the location of the sun.
A controller in the air conditioner controls air conditioning by using a fixed value of the amount of sunlight when change in the amount of sunlight is equal to or lower than a predetermined amount that is obtained by the navigation system while the sunlight is incident into the vehicle.
Preferably, a navigation controller in the navigation system and a controller for the air conditioner are constituted in a common computing device so that the data processing is performed promptly.
Other features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings.